Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/16—Ethene-propene or ethene-propene-diene copolymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing four or more carbon atoms
  • C08L23/0815—Copolymers of ethene with unsaturated hydrocarbons only containing four or more carbon atoms with aliphatic 1-olefins containing one carbon-to-carbon double bond
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/06—Polyethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2203/00—Applications
  • C08L2203/16—Applications used for films
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2207/00—Properties characterising the ingredient of the composition
  • C08L2207/06—Properties of polyethylene
  • C08L2207/066—LDPE (radical process)
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/10—Homopolymers or copolymers of propene
  • C08L23/14—Copolymers of propene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
  • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
  • C08L2666/04—Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/31909—Next to second addition polymer from unsaturated monomers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/31909—Next to second addition polymer from unsaturated monomers
  • Y10T428/31913—Monoolefin polymer

Definitions

• the present invention concerns polyethylene compositions comprising a linear low-density copolymer of ethylene (LLDPE) having a narrow distribution of molecular weights, and a crystalline copolymer of propylene.
• LLDPE linear low-density copolymer of ethylene
• the films obtainable from the said compositions possess an excellent balance of mechanical properties and optical properties.
• compositions are readily processable in the melted state, since they do not require large expenditures of energy in the machines used for their processing and do not cause high pressures at the head in the machines themselves.
• the copolymer of ethylene used for the compositions of the present invention possesses a molecular weight distribution, in terms of the ratio between the average ponderal molecular weight (M w ) and the average numerical molecular weight (M n ), that is in terms of M w /M n , which is particularly narrow (corresponding to values of M w /M n less than 4) and hence typical of the polyethylenes obtained with metallocene catalysts.
• compositions of the present invention differ from the compositions described in the published patent applications WO 93/03078 and WO 95/20009, in which the LLDPE copolymer (which is mixed with a crystalline copolymer of propylene) is prepared with Ziegler-Natta catalysts and hence possesses values of M w /M N typically greater than or equal to 4.
• the LLDPE copolymer is mixed with a copolymer of propylene, however the crystallinity of that copolymer of propylene is rather low, as is indicated by the low values of the enthalpy of fusion (less than or equal to 75 J/g) and, in particular, the degree of crystallinity (less than 35%).
• the addition of the crystalline copolymer of propylene is capable of improving the resistance of the polyethylene film to impact and to tearing.
• compositions comprising an LLDPE copolymer obtained with Ziegler-Natta catalysts and a copolymer of propylene are inferior, in particular as regards the haze and gloss values, to those typical of an LLDPE copolymer obtained with metallocene catalysts and having relatively high F/E ratio values, i.e. greater than 20.
• LLDPE copolymers obtained with metallocene catalysts in general show haze values less than ca. 20% and gloss values greater than ca. 30% (measured on blown film of thickness 25 ⁇ m by the method described in the examples).
• LLDPE copolymers Corresponding to the said high haze and gloss values, such LLDPE copolymers also possess satisfactory impact resistance (Dart Test) and tear resistance (Elmendorf) values.
• the relative quantity of propylene copolymer in the polyethylene compositions is 10% by weight, and the transparency of the films obtained from such compositions is found to be substantially unchanged compared to the transparency of the films obtained from the corresponding LLDPE copolymers in the pure state.
• the films obtained from the aforesaid compositions show high tensile modulus values, superior to those of the films obtained from the corresponding LLDPE copolymers in the pure state, and high breaking strain values.
• the object of the present invention is constituted by polyethylene compositions comprising (percentages by weight):
• compositions of the present invention can contain, in addition to the components A) and B), from 0.5 to 10%, preferably from 1 to 6%, by weight of an LDPE polyethylene (component C), relative to the total weight of A) +B) +C).
• compositions are generally characterized by haze values less than or equal to 25%, preferably less than or equal to 20%, in particular between 20 and 5%, and gloss values greater than ca. 30%, in particular between 30 and 60% (measured on blown film of thickness 25 ⁇ m by the method described in the examples).
• compositions of the present invention are generally characterized by dart test values greater than or equal to 150 g, preferably greater than or equal to 200 g, in particular between 150 and 400 g, preferably between 200 and 400 g (measured on blown film of thickness 25 ⁇ m by the method described in the examples).
• compositions of the present invention show particularly high tear resistance values (Elmendorf), both as such and in consideration of the dart test values.
• Elmendorf tear resistance values
• such values are greater than or equal to 400 g (measured on blown film of thickness 25 ⁇ m by the method described in the examples) in the transverse direction (TD), in particular between 400 and 800 g, and greater than or equal to 150 g in the machine direction (MD), preferably greater than or equal to 200 g, in particular between 150 and 350 g, preferably between 200 and 350 g.
• the component A) of the compositions of the present invention has an ethylene content greater than or equal to 60% by weight, in particular from 60 to 99%, preferably greater than or equal to 70% by weight, in particular from 70 to 99%, more preferably greater than or equal to 80% by weight, in particular from 80 to 99%.
• alpha-olefins CH 2 ⁇ CHR present in the component A) of the compositions of the present invention are propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene.
• Preferred examples are 1-butene, 1-hexene and 1-octene.
• the component A) possesses melt flow rate E values (MFR E according to ASTM D 1238) from 0.1 to 100 g/10 min. Moreover, the said component A) preferably possesses a content of fraction soluble in xylene at 25° C. less than or equal to 5% by weight.
• the DSC (Differential Scanning Calorimetry) trace of the said component A) preferably shows a single melting peak (typical of one crystalline phase); this peak is generally situated at a temperature greater than or equal to 100° 0 C.
• LLDPE copolymers having the characteristics quoted above for the component A) are known in the art and can be obtained by conventional polymerization processes (in gas phase, in suspension or in solution) using catalysts comprising a compound of a transition element, preferably Ti, Zr or Hf, or from the lanthanide series, wherein this element is bound to at least one cyclopentadienyl group, and a cocatalyst, in particular an alumoxane or a compound capable of forming an alkyl cation.
• a transition element preferably Ti, Zr or Hf
• a cocatalyst in particular an alumoxane or a compound capable of forming an alkyl cation.
• alpha-olefins CH 2 ⁇ CHR I present in the component B) of the compositions of the present invention are 1-butene, 1-pentene, 4-methylpentene-1, 1-hexene and 1-octene. 1-butene is preferred.
• the component B) has melt flow rate L values (MFR L according to ASTM D 1238) from 0.1 to 500 g/10 min, preferably from 1 to 50, more preferably from 6 to 25 g/10 min.
• the said component B) has density values (measured according to ASTM D 4883) less than 0.9 g/cm 3 , in particular from 0.890 to 0.899, more preferably from 0.892 to 0.899.
• the said component B) preferably possesses the following characteristics:
• enthalpy of fusion measured according to ASTM D 3418-82 greater than 50 J/g, more preferably greater than or equal to 60 J/g, in particular greater than or equal to 70 J/g, for example from 75 to 95 J/g;
• melting point (measured according to ASTM D 3418-82) less than 140° C., more preferably from 120 to 140° C.;
• the crystalline copolymers of propylene having the characteristics quoted above for the component B) are known in the art, and can be obtained by conventional polymerization processes using stereospecific Ziegler-Natta catalysts supported on magnesium halides.
• Such catalysts contain, as an essential component, a solid catalytic component comprising a compound of titanium having at least one titanium-halogen bond and one electron-donor compound, both supported on a magnesium halide.
• a solid catalytic component comprising a compound of titanium having at least one titanium-halogen bond and one electron-donor compound, both supported on a magnesium halide.
• an Al-alkyl compound and an electron-donor compound are generally used.
• Catalysts having the aforesaid characteristics are for example described in the U.S. Pat. No. 4,399,054 and in the European patent 45977.
• the LDPE polymer (low density polyethylene) constituting the component C) of the compositions of the present invention is a homopolymer of ethylene or a copolymer of ethylene containing smaller quantities of comonomers, such as butyl acrylate, prepared by polymerization at high pressure using free radical initiators.
• the density of the said LDPE polymer generally ranges from 0.910 to 0.925 g/cm 3 (measured according to ASTM D 4883).
• the MFR E values of the said LDPE polymer generally range from 0.1 to 50 g/10 min, preferably from 0.3 to 20 g/10 min.
• LDPE polymers having the characteristics quoted above for the component C) are known in the art. Specific examples are the commercially available polymers with the brand names Escorene, and Lupolen (BASF).
• compositions of the present invention can contain other polymeric components, such as olefin elastomers, in particular ethylene/propylene (EPR) or ethylene/ propylene/diene (EPDM) elastomers, and additives commonly used in the art, such as stabilizers (in particular phenolic antioxidants and process stabilizers such as the organic phosphites), pigments, fillers, nucleating agents, release agents, lubric-ating and antistatic agents, flame retardants and plasticizers.
• EPR ethylene/propylene
• EPDM ethylene/ propylene/diene
• compositions of the present invention can be prepared by processes of polymerization in two or more consecutive stages, using in at least one stage the catalysts described above for the preparation of the component A) and in at least one other stage the Ziegler-Natta catalysts described above for the preparation of the component B), and optionally adding the component C) by mixing in the melted state.
• compositions of the present invention by mixing of the components A), B), and optionally C), in the melted state.
• the processes of mixing in the melted state advantageously used are of conventional type and are based on the use of mixing devices known in the art, such as single-screw and double-screw extruders.
• compositions of the present invention are particularly suitable for the preparation of moulded articles in general, and in particular of film, monolayer or multilayer, whether cast or mono- or biaxially oriented, including blown films, in which at least one layer comprises the aforesaid compositions.
• the product from this stage is a tubular extrudate which is then inflated with air,- to obtain a tubular bubble which is cooled and collapsed to obtain the film.
• the aforesaid propylene copolymers are prepared using Ziegler-Natta catalysts of high yield and stereospecificity, supported on magnesium chloride, in the polymerization.
• Temperature profile 185, 195, 200, 205, 210, 215, 235, melted 230° C.;
• the relative quantities of the aforesaid components are equal to 80% by weight of A) and 20% by weight of B), relative to the total weight of the composition.
• a blown film of 25 ⁇ m thickness is prepared using a COLLIN-25 machine under the following conditions:
• Temperature profile 155, 165, 175, 185, 190, 190, 190, melted 200° C.;
• Screw revolutions 90 rpm; Throughput: 4.2 kg/h;
• Table 1 The properties shown in Table 1 are measured on the film thus prepared. For comparison purposes, Table 1 also shows the properties of a blown film obtained and subjected to testing under the same conditions as in Example 1, but using the component A) in the pure state (Reference Example 1).
• the head pressure corresponds to the pressure measured at the head of the extruder while the motor input relates to the extruder motor.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
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• Materials For Medical Uses (AREA)

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Citations (9)

• 1998
  • 1998-07-07 IT IT98MI001548A patent/ITMI981548A1/it unknown
• 1999
  • 1999-07-02 DE DE69925492T patent/DE69925492T2/de not_active Expired - Lifetime
  • 1999-07-02 CZ CZ200180A patent/CZ200180A3/cs unknown
  • 1999-07-02 CA CA002336816A patent/CA2336816A1/en not_active Abandoned
  • 1999-07-02 AT AT99931240T patent/ATE296333T1/de not_active IP Right Cessation
  • 1999-07-02 US US09/743,123 patent/US6462134B1/en not_active Expired - Fee Related
  • 1999-07-02 CN CN99810171A patent/CN1314929A/zh active Pending
  • 1999-07-02 WO PCT/EP1999/004596 patent/WO2000002961A1/en not_active Ceased
  • 1999-07-02 EP EP99931240A patent/EP1100846B1/en not_active Revoked
  • 1999-07-02 KR KR1020017000224A patent/KR20010053418A/ko not_active Withdrawn
  • 1999-07-02 AU AU47812/99A patent/AU4781299A/en not_active Abandoned
  • 1999-07-02 JP JP2000559187A patent/JP2002520439A/ja active Pending
  • 1999-07-02 BR BR9912251-0A patent/BR9912251A/pt not_active IP Right Cessation
• 2001
  • 2001-01-05 NO NO20010086A patent/NO20010086L/no not_active Application Discontinuation

Patent Citations (10)

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